The primary function of the skin is to protect the body against environmental stresses and to prevent against dehydration.
TEWL is a term used in dermatology to characterize the loss of water that passes from the inside of a body through the epidermal layer (skin) to the surrounding atmosphere via diffusion and evaporation processes.
TWEL is also the most physiological readout to assess compromised skin barrier function as it is well established that an impaired skin barrier eventually leads to loss of water throughout the skin.
Transepidermal water loss can have genetic and/or environmental etiology. Specifically, it can be the results of a genetic polymorphism leading to a decrease in protective protein expression and thus compromised skin barrier. Skin inflammation, mainly caused by an external irritant, can also lead to water loss. Both genetic and environmental components can together or separately lead to excessive transepidermal water loss and ultimately trigger different TEWL-associated skin diseases that range from dry skin to more severe conditions such as eczema.
Transepidermal water loss having a genetic component can lead to dry skin or reactive skin or eczema. When this water loss has an environmental component and is for instance linked to the exposure to an allergen through the skin, this can lead to an allergic eczema/atopic dermatitis, i.e. an eczema accompanied by allergic sensitization.
For the establishment of eczema and reactive skin a genetic predisposition (polymorphism in genes such as filaggrin gene or SPINK5) and an irritant such as for example soap, transpiration, stress, cold, wool, allergens are usually necessary for the development of the disease. Subjects suffering from eczema show reactions of the skin against agents that usually do not cause any skin irritation in healthy subjects (like soap, cold, transpiration, stress, wool, allergen).
In TEWL-associated disorders, the normal water loss rate is increased due to a diminished barrier function of the epidermis. A TEWL-associated disorder is thus mainly characterized by the symptoms of a dehydrated epidermis like dry or scaly skin. In humans, TEWL associated disorders are often associated with atopic dermatitis (also called eczema) and/or reactive skin (like winter rashes). Other diseases with an increased TEWL and skin inflammatory condition comprise chronological aging, injury, infection and/or severe damage as in the case of burns, psoriasis, and a range of inflammatory skin conditions such as atopic diathesis in rosacea and perioral dermatitis.
Measurement of TEWL is thus a way to measure loss of water through the epidermal layer (skin) and is considered as one of the best marker for skin barrier function and consequently for the risk of developing a skin associated disease.
Indeed, an increased TEWL at 2 days and 2 months in infant predicts for eczema at 1 year of age. (Skin barrier dysfunction measured by transepidermal water loss at 2 days and 2 months predates and predicts atopic dermatitis at 1 year: Maeve Kelleher et al. JACI 2014.) and the enhancement of skin barrier function from birth to 6 months significantly decrease (50%) the risk of developing eczema. (Emollient enhancement of the skin barrier from birth offers effective atopic dermatitis prevention. Simpson E L. JACI 2014).
TEWL measurement can also be used to assess and quantify the clinical outcome of a skin disease.
It is therefore the object of the present invention to provide a composition for maternal administration for the prevention or treatment of transepidermal water loss and/or TEWL-associated disorders and/or to enhance the skin barrier function in the off-spring or breast-fed infant. Preferentially, this composition is administered to a pregnant and/or lactating woman.